1. Field of the Invention
The present invention relates to a substrate processing apparatus for treating the surface of a substrate such as an LCD (liquid crystal display) glass substrate, a PDP (plasma display panel) glass substrate or a semiconductor wafer, and the substrate processing apparatus is applicable to the fabrication of LCDs, PDPs, semiconductor devices and the like.
2. Description of the Related Art
Fabrication processes for LCDs, PDPs and ICs (integrated circuits) include the step of forming electronic circuits on a substrate such as a glass substrate or a wafer. A special-purpose substrate processing apparatus is used for the formation of electronic circuitry on a substrate. A substrate processing apparatus of this type generally has a plurality of units including a unit for cleaning the surface of a substrate and a unit for patterning a metal film on the surface of the substrate.
One exemplary construction of such a substrate processing apparatus is of a sequential transportation type, which is shown in plan in FIG. 15. The apparatus of the sequential transportation type has a loader L to be loaded with a cassette 101 holding a plurality of untreated substrates 100, a plurality of processing units S, and an unloader U to be loaded with a cassette 102 for storing treated substrates 100. The loader L, the processing units S and the unloader U are linearly arranged in the X direction in this order.
One of the substrates 100 held in the cassette 101 placed on the loader L is carried out by means of a carry-out robot 103, and transferred to a transportation robot R disposed adjacent to the carry-out robot 103 on the +X side thereof. The transportation robot R transfers the substrate 100 to a processing unit S disposed adjacent to the transportation robot 103 on the +X side thereof. The substrate 100 treated by the processing unit S is carried out by a second transportation robot R disposed adjacent to the processing unit S on the +X side thereof and, transferred to a second processing unit S disposed adjacent to the second transportation robot R on the +X side thereof. Thus, the substrate 100 is subjected to a series of processes while being sequentially transported in the +X direction. Finally, the substrate 100 is transferred to a carry-in robot 104, and brought into the cassette 102 placed on the unloader U by means of the carry-in robot 104.
However, the apparatus of the sequential transportation type has a great length as measured in the X direction, because the processing units S are linearly arranged with the transportation robots R interposed therebetween. Therefore, if a greater number of processing units S are to be provided in the apparatus, a much greater floor area is required for the installation of the apparatus.
Further, since the arrangement order of the processing units absolutely determines the process order in which one substrate is subjected to a plurality of processes, it is difficult to change the process order.